Thickness‐ and Particle‐Size‐Dependent Electrochemical Reduction of Carbon Dioxide on Thin‐Layer Porous Silver Electrodes

Abstract The electrochemical reduction of CO 2 can not only convert it back into fuels, but is also an efficient manner to store forms of renewable energy. Catalysis with silver is a possible technology for CO 2 reduction. We report that in the case of monolithic porous silver, the film thickness and primary particle size of the silver particles, which can be controlled by electrochemical growth/reduction of AgCl film on silver substrate, have a strong influence on the electrocatalytic activity towards CO 2 reduction. A 6 μm thick silver film with particle sizes of 30–50 nm delivers a CO formation current of 10.5 mA cm −2 and a mass activity of 4.38 A g Ag −1 at an overpotential of 0.39 V, comparable to levels achieved with state‐of‐the‐art gold catalysts.